Polyaminoacids as builders for formulations of detergents

ABSTRACT

This invention relates to use of polyaminoacids as builders or co-builders in the formulation of detergents. These polyaminoacids, which are highly efficient as complexing agents, have good resistance to heat and stability to pH and are entirely biodegradable, have been chosen among those having the general formula: ##STR1## with substituents which are defined in the following description. The formulations of detergents contain, apart from the above builders, surface active agents, alumina-silicates and additives chosen from neutral salts, enzymes, bleaching agents, stabilizers, anti-foaming agents, perfumes, bactericides.

FIELD OF THE INVENTION

The present invention concerns the use of polyaminoacids or theirderivatives, as builders or co-builders in the formulation ofdetergents. These products are very efficient as complexing agents, showa good stability to heat and to pH, and are also entirely biodegradable.

BACKGROUND OF THE INVENTION

It is now well-known that products used for detergents are mostlyresponsible for the presence of phosphorous in water: among these theeffect of sodium tripolyphosphate (STPP), used as a builder, has beenparticularly studied.

It is also well known that many efforts have been made in research tofind an alternative to polyphosphates. But the various solutionsattempted have not always given satisfactory results in that, when theSTPP is removed or decreased, the variations which occur in the finalresults of the washing process are greater than those which would havebeen expected because of the sole decrease of the sequestering power ofthe detergent matrix.

This is due to the fact that it is impossible to find out a productwhich possesses the multiple characteristics of STPP, i.e. control ofwater hardness, buffer action, dirt dispersion and prevention ofre-depositing.

Among the builders, citric acid and its salts, zeolites, nitryltriaceticacid (NTA) or polymeric polycarboxylic acids are now used.

Citric acid and sodium citrate are the main builders used in detergentliquids as they are the only ones which do not interfere with theenzymes present. Their percentage in these formulations is around 1-2%.

They represent 5% of the total market of builders.

They have the advantage of being entirely biodegradable, non-toxic, ofbeing highly compatible with the other components of detergents and ofhaving an effect of synergism with other builders (for examplezeolytes).

Their use is limited by their efficiency. Their effectiveness quicklydecreases with the temperature increase (T>50° C.). They have lowersequestering and dispersion power than polyphosphates (STPP).

Zeolytes are used in powder formulations.

As far as their toxic effect on the environment is concerned, theseproducts are acceptable. They do not present any risk for water and donot increase the BOD load in plants for the treatment of waste water,even if, being insoluble. They do leave large quantities of sedimentsand materials in suspension.

As far as their detergency is concerned, they have a good absorbingcapacity with respect to colored substances and pigments given out byfabrics. Their effectiveness as ion exchangers increases with thetemperature. On the contrary, their ion exchange kinetics are slow, theyhave no buffer action and no dispersion power.

They are used in combination with other builders.

Nitrilotriacetic acid (NTA), after being initially accepted as apossible substitute for STPP, was then almost completely abandonedbecause of the numerous environmental problems involved.

As far as its efficiency as a detergent is concerned, its power as acomplexing agent is 1.5 times higher than that of STPP and itsperformance is almost double in formulations for cold water. It has abetter buffer effect, it is a good re-depositing prevention agent. Itimproves the effectiveness of optical bleaches. It stabilizes foams andperborates. It does not hydrolize during the washing process. Itincreases the solubility of some anionic surface-active agents (LAStype), and it is compatible with other components. It has thedisadvantage of decolorizing colored fabrics based on metal complexesand has the tendency to agglomerate.

The real reason for its being abandoned, however, is due to the hightoxicological risks involved in its use.

Its biodegradability is extremely limited, and the slime used for itsprocessing requires a long acclimatation period. The rate of thisprocess seems too slow to be able to keep up with the high fluctuationsof NTA concentration, thus preventing its complete removal. Thesituation becomes worse in the processing of sea water and generallywhen the water hardness and NTA concentration increase.

The degradation of NTA is very limited also under anaerobic conditions.The above situation can have serious consequences: penetration andpollution of the water-tables damage to phytoplancton which cannotsurvive NTA concentrations higher than 1000 micrograms/liter with a riskof interrupting the feedingchain. The formation of complexes with theheavy metals present in the sediments, which go back again intosolution, increase the risk of genetical changes and tumors.

The most valid polymeric polycarboxylic acids have been proved to becopolymers made up of acrylic acid and maleic anhydride.

These products are good complexing agents, they have a good dispersionand re-depositing prevention capacity, they improve the structure of thedetergents by preventing the formation of lumps.

The main problem which limits their use is associated with their lack ofbiodegradability. It seems that polycarboxylates are accepted in Europebecause they are protected by German legislation, for which it issufficient for builders to be eliminated from water but not necessarilyfrom the environment. This means that products are accepted which arenot biodegradable (and thus cannot be eliminated from the environment)but are absorbed into the membranes of bacteria and in this way,eliminated from water.

It is precisely the biodegradability which stimulated further researchon an alternative detergency. This brought about the study of copolymersof maleic anhydride and/or acrylic acid with natural substances such asstarch or dextrine, copolymers of maleic anhydride and substancescapable of introducing allylic and vinylic groups, copolymers of maleicanhydride/ethylene oxide, copolymers of glyoxylic acid/formaldehyde,etc. However results are still far from reaching expectations. Atpresent, most detergents contain between 2 and 4% of polymers, mainlyacrylic/maleic polymers combined with other builders.

It is also known (English patent No. 1404814) that polyaminoacids canact as surface-active agents, in that they are obtained through areaction between polyimidic derivatives and long-chain aliphatic amines.By controlling the type of chain of the latter or the degree ofpolymerization of the polyimide, it is possible to choose the finalcharacteristics of the polyaminoacid under examination.

However, the products described in the English patent do not seem tohave sufficiently high characteristics to enable them to be useddiversely or in any specific way that has not been already indicated.These characteristics may be summarized as follows: biodegradability,non-toxicity, no irritating effects, high solubility in water which,together with the detergent properties, determine the applicability andversatility of use in subsequent formulations.

DETAILED DESCRIPTION OF THE INVENTION

Applicants have now discovered that polyaminoacids or their derivativescan be used as builders or co-builders in the formulation of detergents,having excellent properties as complexing agents with respect to calciumand preventing the formation of CaCO₃ crystals; the above products arealso extremely efficient complexing agents, have a good resistance toheat and stability to pH, they are not toxic, do not irritate and areentirely biodegradable therefore eliminating all environmental problems.

The detergent base, made up of polyaminoacids and anionic and/or nonionic and/or amphoteric surface-active agents can be used withconventional products such as enzymes, bleaching agents, stabilizers,neutral salts, anti-foaming agents, perfumes, bactericides, etc.

Applicants point out that the results are even more surprising in thatit is well-known that amino acids such as L-aspartic acid and L-glutamicacid, although having good capacities as complexing agents as regards totransition metal such as Fe, Co and Ni, are not able to form stablecomplexes with alkali or alkaline earth metals (Angew--Chem. Ind. Ed.Engl. 29 (1990) 1090-1103).

The present invention consequently concerns a group of polyaminoacidsand their derivatives having the following general formula (I) which canbe used as builders and co-builders. ##STR2## in which, m can be equalto 0, 1, 2; n has a value between 5 and 2000; R can be: H, CH₃, COY, CH₂COY, CH₂ CH₂ COY, CH₂ CH₂ CH₂ NHC═(NH₂)NH, CH₂ SH, CH₂ CH₂ CH(OH)CH₂NH₂, CH₂ CH(CH₃)₂, CH(CH₃)CH₂ CH₃, ##STR3## wherein Y can be:

--OZ wherein Z represents H or a C₁ -C₁₅ alkyl radical; or --NZZ'wherein Z and Z' are the same or different from one another, andrepresent H or a C₁ -C₁₅ alkyl radical.

These amino acids have a molecular weight of between 300 and 200,000.

The products belonging to the above formula (I) can be prepared usingthe well-known methods for the synthesis and which can be used by allexperts in the field, depending on the type of substituents required andthe number of carbon atoms.

For example, for m=0, the amino acids, possibly protected, can bereacted with phosgene or its derivatives, thus obtaining thecorresponding N-carboxy-anhydrides (ref.: A. J. Domb, E. G. Cravalho andR. Langer; J. Polymer Science part. A Polym. Chem., 1988, 26, 2623 ):##STR4## were R has the above meaning; R' and R", either alike ordifferent in the same molecule, can be Cl, OCCl₃, OR'" (were R'" can bean alkyl or aryl group having from 1 to 15 carbon atoms).

The N-carboxy-anhydrides thus obtained are polymerized in the presenceof bases which act as catalysts (for example amines, or bases made byelectrolysis), giving structures of type (I).

Polymers having general formula (I) with m=0, 1, 2, can be obtained bythermal polymerization of amino acids obtaining the correspondingpolyamides (ref.: S. W. Fox, K. Harada, JACS, 1958, 80, 2694; S. W. Fox,K. Harada, JACS, 1960, 82, 3715).

Among all possible amino acids having formula (I), those derived fromaspartic acid, glutamic acid and their mixtures have proved to be themost effective.

It is therefore possible to formulate detergent compositions with thesepolyaminoacids (either alone or in mixtures), in percentages of between5 and 50% by weight, together with, naturally, one or moresurface-active agents (10-40%), at least one zeolyte (0.5-70%), and oneor more additives chosen from neutral salts, enzymes, bleaching agents,stabilizers, antifoaming agents, perfumes and bactericides.

EXAMPLES

The effectiveness of the present products will be shown herebelow inrelation to their activity as Calcium complexing agents through thefollowing non-limiting examples.

Their activity as complexing agents was established by using a selectiveelectrode for ion Ca⁺⁺, coupled with a counter-electrode of calomel.

EXAMPLE 1

The solution of the complexing agent was prepared by adding 51 mg ofpolyaspartic acid with n=4, to 100 ml of a water solution containingNaCl 1M and buffered at pH 10 (NH₃). 1 ml of a solution of CaCl₂ 0.1Mwas added at a constant temperature of 25° C. The residual concentrationof Ca⁺⁺ both after 5 and 30 minutes was equal to 7.10⁻⁴ M.

EXAMPLE 2

53.46 mg of the amide of the polyaspartic acid with n=4 were added tothe above buffered solution. 1 ml of a solution of CaCl₂ 0.1M was addedat a constant temperature of 25° C. The residual concentration of Ca⁺⁺both after 5 and 30 minutes was equal to 7.10⁻⁴ M.

EXAMPLE 3

52.69 mg of the amide of the polyaspartic acid with n=8 were added tothe buffered solution. 1 ml of a solution of CaCl₂ 0.1M was added at aconstant temperature of 25° C. The residual concentration of Ca⁺⁺ bothafter 5 and 30 minutes was equal to 2.10⁻⁴ M.

EXAMPLE 4

101.52 mg of the polymer of the polyaspartic acid with n>150 were addedto the buffered solution. 2 ml of a solution of CaCl₂ 0.1M was added ata constant temperature of 25° C. The residual concentration of Ca⁺⁺after 5 minutes was equal to 6.10⁴ M and after 30 minutes was equal to3.10⁻⁵ M.

EXAMPLE 5

103.88 mg of polyglutamic acid with n>100 were added to the bufferedsolution. 1 ml of a solution of CaCl₂ 0.1M was added at a constanttemperature of 25° C. The residual concentration of Ca⁺⁺ after 30minutes was equal to 10⁻⁴ M.

EXAMPLE 6

50 mg of polyaspartic acid with n=4 were added to the buffered solution.1 ml of a solution of CaCl₂ was added at a constant temperature of 60°C. The concentration of Ca⁺⁺ both after 5 and 30 minutes was equal to5.10⁻⁴ M.

EXAMPLE 7

49 mg of the amide of polyaspartic acid with n=4 were added to thebuffered solution. 1 ml of a solution of CaCl₂ 0.1M was added at aconstant temperature of 60° C. The final concentration of Ca⁺⁺ after 30minutes was equal to 5.10⁻⁴ M.

EXAMPLE 8

50 mg of the amide of polyaspartic acid with n=8 were added to thesolution. 1 ml of a solution of CaCl₂ 0.1M was added at a constanttemperature of 60° C. The concentration of Ca⁺⁺ after 30 minutesdecreased to 3.10⁻⁴ M.

EXAMPLE 9

49 mg of polyaspartic acid with n>150 were added to the solution. 1 mlof a solution of CaCl₂ 0.1M was added at a constant temperature of 60°C. The concentration of Ca⁺⁺ after 30 minutes decreased to 1.10⁻⁴ M.

EXAMPLE 10

51 mg of polyglutamic acid with n>100 were added to the solution. 1 mlof a solution of CaCl₂ 0.1M was added at a constant temperature of 60°C. The residual concentration of Ca⁺⁺ after 30 minutes was equal to2.10⁻⁴ M.

Washing tests were carried out on formulations containing the abovepolyaminoacids as builders or co-builders, as described below, using asa comparison, a similar system with the exception that thepolyaminoacids were substituted by acrylic/maleic copolymers.

In these formulations, the components are present in quantities includedin the following ranges:

5-50% by weight of polyaminoacids

10-40% by weight of anionic and/or non ionic and/or amphotericsurface-active agents

5-50% by weight of sodium alumino-silicates

0.5-70% by weight of neutral salts, enzymes, bleaching agents,stabilizers, anti-foaming agents, perfumes, bactericides, water.

EXAMPLE 11

0% Polyaminoacids

12% alkylbenzenesulfonates (C₉ -C₁₅)

25% sodium aluminosilicates

25% sodium perborate

23% sodium sulfate

5% water

EXAMPLE 12

15% polyaminoacids

20% ethoxylated n-alcohols (C₁₂ -C₁₆) (n=10-15)

20% sodium aluminosilicates

20% sodium perborate

20% sodium sulfate

5% water

EXAMPLE 13 comparison sample

10% akrylic/maleic copolymer

12% alkylbenzenesulfonates (C₉ -C₁₅)

25% sodum aluminosilicates

25% sodium perborate

23% sodium sulfate

5% water

As pointed out in the introduction, acrylic acid/maleic anhydridecopolymers are good complexing agents, have a high dispersion andprecipitation-preventing power, and also prevent the formation of lumps.

Furthermore, the use of builders according to the present invention(formulations corresponding to examples 11 and 12) produce compositionswhich have detergent properties at least equal to those containing theabove-mentioned copolymers. The degree of whiteness obtained is in factnever inferior to that of compositions known to date.

However, the builders used in the detergent formulations in accordancewith the present invention, are substantially completely biodegradable,which represents a definite advantage over other known detergentformulations.

Washing tests were also carried out in a washing-machine with adetergent formulation containing zeolyte both in the presence of andwithout a polyaminoacid.

EXAMPLE 14

The tests were made with the following formulation:

    ______________________________________                                        Surface-active agent            14.0%                                         Zeolyte                         27.0%                                         Carbonate                       10.0%                                         Enzyme                           0.4%                                         Polyaspartate                    0%                                           Sulfate                         22%                                           Perborate 4                     20.0%                                         Silicate 2                       3.0%                                         Water                  approx.   3.6%                                         Working conditions:                                                           30°                                                                    90° C.                                                                 Without CMC (carboxymethylcellulose)                                          3-6 washing cycles                                                            ______________________________________                                    

The actual performance during the washing process was evaluated asfollows:

A) DETERGENCY

The study was carried out using a standard dirty strip type EMPA 103.

The following observations were made:

there were no negative influences; behavior in the presence of thepolyaminoacid was better than it was with the zeolyte alone;

results were particularly positive in the case of cocoa andblood/milk/China ink stains;

the surface-active agent has an effect of synergism thus improving theoverall cleansing action.

B) SECONDARY EFFECTS OF THE WASHING PROCESS (CRUST FORMATION)

the amount of crusting decreases with respect to when zeolyte alone isused.

as the complexing power is low, it can be assumed that it has a gooddispersion effect for the crusting (and also for the dirt);

even better results are expected (with respect to zeolyte alone) if 15washing cycles are carried out.

The detergency activity of polyaspartate is presumably brought aboutthrough its high dispersion capacity of both the dirt and crusting salts(it does not allow these to deposit). Although the invention has beendescribed in conjunction with specific embodiments, it is evident thatmany alternatives and variations will be apparent to those skilled inthe art in light of the foregoing description. Accordingly, theinvention is intended to embrace all of the alternatives and variationsthat fall within the spirit and scope of the appended claims. The abovereferences are hereby incorporated by reference.

We claim:
 1. A detergent formulation containing 10 to 40% by weight ofat least one surface active agent, from 5 to 50% of weight of at leastone sodium aluminosilicate, from 0.5 to 70% by weight of at least oneadditive chosen from neutral salts, enzymes, bleaching agents,stabilizers, anti-foaming agents, perfumes, bactericides and from 5 to50% by weight of a builder or cobuilder which is at least one polyaminoacid chosen from those having the formula: ##STR5## in which m can be 1or 2; n is between 100 and 2000; R is a radical chosen from: H, CH₃,COY, CH₂ COY, CH₂ CH₂ COY, CH₂ CH₂ CH₂ NHC═(NH₂)NH CH₂ SH, CH₂ CH₂CH(OH)CH₂ NH₂, CH₂ CH(CH₃)₂, CH(CH₃)CH₂ CH₃, CH₂ CH₂ CH₂ CH₂ NH₂, CH₂CH₂ SCH₃, ##STR6## wherein Y can be: --OZ wherein Z represents H or a C₁-C₁₅ alkyl radical; or --NZZ' wherein Z and Z' are the same or differentfrom one another, and represent H or a C₁ -C₁₅ alkyl radical.
 2. Adetergent formulation according to claim 1, wherein the builder orcobuilder is polyaspartic acid.
 3. A detergent formulation according toclaim 1, wherein the builder or cobuilder is polyglutamic acid.